In an image forming apparatus of an electrophotographic type, a photosensitive drum, for example, is uniformly charged by a charger. The charged surface of the photosensitive drum is exposed by light from an exposure device, so that an electrostatic latent image is formed thereon. The electrostatic latent image on the surface of the photosensitive drum becomes a developer image as developers are supplied thereto. After that, the developer image is transferred onto a sheet.
In the image forming apparatus, as the exposure device, there has been known an exposure device having an exposure head. Also, an image forming apparatus has been known in which a process cartridge having a photosensitive drum is detachably mounted to the image forming apparatus. The exposure head has a plurality of light emitting devices consisting of organic EL (Electro Luminescent) devices or LEDs (Light Emitting Diodes) and lenses, which are arranged in an array shape on a part facing a surface of the photosensitive drum. The lights from the light emitting devices are imaged on the surface of the photosensitive drum by the lenses, so that an electrostatic latent image is formed on the surface of the photosensitive drum.
Since the exposure head has a short lens focal length, it is necessary to arrange the exposure head adjacent to the surface of the photosensitive drum. Therefore, the exposure head may interfere with the attaching and detaching operations of the process cartridge.
Accordingly, related-art describes a configuration in which the exposure head (LED array head) is contacted and separated to and from the photosensitive drum in conjunction with opening and closing operations of an exterior cover provided to a front face of an apparatus main body. Specifically, the LED array head is fixed to an upper end portion of an arm-shaped holder that extends in an upper-lower direction. The arm-shaped holder is rotatably mounted to the apparatus main body. As the arm-shaped holder is rotated in conjunction with opening and closing operations of a top cover, the LED array head of the holder is contacted and separated to and from the photosensitive drum.